Download Meaning and Effects 2014-2015 Mechanical or Physical Weathering

Geography
Standard VIII
WEATHERING – Meaning and Effects
2014-2015
Mechanical or Physical Weathering
Q.1.Give examples of internal and external processes that result in the formation of
landforms on the surface of the Earth.
Ans:
PROCESSES THAT RESULTS
THE FORMATION OF
LANDFORMS
External processes
processes –
ExteExrnal
like weather, rivers,
Weather,
Rivers,
glaciers,
wind,
Glaciers,
Wind,
waves, underground
Wavesunderground
water
water
Internal processes –
Earthquakes,
volcanic
eruptions, shifting of
tectonic plates, folding&
faulting
Q.2. (a).Define:i. Weathering- Weathering is the process that consists of disintegration and decomposition of
rocks on the surface of the Earth due to atmospheric conditions.
ii.Erosion:- Erosion is wearing and carrying away of eroded materials on the surface of the
Earth by the agents like running water, glaciers, wind and waves.
iii.Gradation:- The dynamic process that involves the movement of materials from high to
low areas which results in the transportation & deposition of broken or eroded rock material
due to gravity is known as Gradation.
(b) What do the words disintegration and decomposition mean?
Disintegration –It refers to the physical break up of rocks into smaller fragments.
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Decomposition- It refers to change in the chemical composition of minerals present in the
rocks.
Q.3.Name the different types of Weathering.
Ans.
Physical/Mechanical Weathering
Chemical Weathering
Biological Weathering
Q.4. What is physical weathering? State its features.
Ans. The physical break-up of rocks into smaller fragments is known as Physical Weathering.
Main feature
present in the rocks.
No change in the composition or chemical nature of the minerals
Q.5. State the four processes or ways of Mechanical or Physical Weathering.
Ans: The four processes of Mechanical Weathering are



Granular Disintegration
Exfoliation
Frost Action
Block Disintegration
Q.6. What is granular Disintegration?
Ans. Temperature changes (temperature contrasts) leads to expansion due to heating and
contraction due to cooling. This not only occurs between summer & winter but also between
day & night temperatures. Such alternating expansion & contraction between day & night
leads to break-up of the rocks into smaller fragments & different minerals. This is known as
Granular Disintegration.
Q.7. Explain the processes of Exfoliation and Frost Action?
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Ans. Exfoliation- This is more common in arid regions. The peeling away of the surface
layers of the rocks made up of homogeneous minerals ( same type of minerals) is called
Exfoliation. In the arid regions the alternate heating & expansion of the surface layer in the
day & cooling and contraction of the surface layers at night results in such kind of
weathering. This leads to the formation of Exfoliation Domes.
Frost Action- It is seen in the temperate latitudes where temperature is above the freezing
point during the day and below the freezing point during the night. Due to this water present
in the joints or fissures of rocks freeze into ice at night, expands in volume and widens the
cracks by exerting pressure leading to breaking down of rocks known as Frost Action.
Q.8. In what climatic regions is mechanical weathering by Frost Action more potent?
Ans. In temperate latitudes, where the temperature drops resulting freezing of water, frost
action is more potent.
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